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Wheal
	; A wheal or welt on the skin of a man's neck
ICD-10	L50.9
ICD-9	708
DiseasesDB	13606
MedlinePlus	000845
eMedicine	med/3014

For other uses, see Wheal (disambiguation).

A wheal or wheal response, also called a welt or weal (in the UK), is a firm, elevated swelling of the skin.^[1] Wheals are generally pale red in color, although color can also be deep red or purple. They may be round, oval, gyrate, annular^[1] or irregular/serpiginous in shape and are usually rounded or flat topped.^[2] When they are irregular/serpiginous in shape, wheals often appear with pseudopods. Wheals are usually well demarcated^[2] and often itch or have a burning sensation. They typically disappear within 24-48 hours.^[1] An itchy rash consisting of wheals may be called urticaria (known individually as a uticarial exanthem) or, more commonly, hives.

[edit] Causes

Wheals are due to fluid build up in the skin as a result of a blow or lash to the skin, or an allergic reaction to innumerable initiating agents such as drugs or insect bites. These cause edema in the papillary body of the dermis. Wheals may also be produced with Darier's sign, and by stroking the skin of certain normal persons who demonstrate the phenomenon called dermatographism.^[3] Wheals may be formed by the injection of fluid with a hypodermic syringe.

While the borders are sharp, they are not stable, and as this short-lived papillary edema shifts, each wheal transiently moves^[4] from involved to adjacent uninvolved areas over a period of hours. Also note, while this finding is usually pale red, if the amount of edema is adequate to compress superficial vessels, the wheal may have a white center.^[3] The epidermis is not affected and there is no scaling.^[3]

[edit] See also

[edit] Footnotes

^ ^a ^b ^c Braunwald, Eugene; Fauci, Anthony; Kasper, Dennis; Hauser, Stephen; Longo, Dan; Jameson, Larry, ed (2001). Harrison's principles of internal medicine (15th Edition ed.). New York: McGraw-Hill. pp. 95 & 306. ISBN 0070072728.
^ ^a ^b Lee Goldman, Lee; Ausiello, Dennis, ed (2004). Cecil textbook of medicine (22nd ed. ed.). Philadelphia: W.B. Saunders. p. 2451. ISBN 0-7216-9652-X.
^ ^a ^b ^c Fitzpatrick, Thomas B. ed., ed (1986). Dermatology in general medicine: textbook and atlas. New York: McGraw-Hill. pp. 29–30. ISBN 0070796890.
^ Habif, Thomas P. (2004). Clinical dermatology: a color guide to diagnosis and therapy. St. Louis: Mosby. p. 825. ISBN 0-323-01319-8.

[Harrison.27s_15-0] Braunwald, Eugene; Fauci, Anthony; Kasper, Dennis; Hauser, Stephen; Longo, Dan; Jameson, Larry, ed (2001). Harrison's principles of internal medicine (15th Edition ed.). New York: McGraw-Hill. pp. 95 & 306. ISBN 0070072728.

[Cecil_22-1] Lee Goldman, Lee; Ausiello, Dennis, ed (2004). Cecil textbook of medicine (22nd ed. ed.). Philadelphia: W.B. Saunders. p. 2451. ISBN 0-7216-9652-X.

[isbn0070796890-2] Fitzpatrick, Thomas B. ed., ed (1986). Dermatology in general medicine: textbook and atlas. New York: McGraw-Hill. pp. 29–30. ISBN 0070796890.

[isbn0-323-01319-8-3] Habif, Thomas P. (2004). Clinical dermatology: a color guide to diagnosis and therapy. St. Louis: Mosby. p. 825. ISBN 0-323-01319-8.

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